Helicobacter pylori, a Gram-negative bacterium, is responsible for one of one of the most common bacterial infections, affecting about 50% of the human population. H. pylori was first discovered in 1982, and subsequently found to be a major causative agent of gastritis, gastric and duodenal ulcers, and gastric cancer. The World Health Organization classified H. pylori as a Group 1 carcinogen. We initiated the H. pylori project to study the transcriptional regulation in the pathogenesis of the bacterium. Specifically, we will focus on 1) the study of the transcription machinery and on the regulation of virulence gene expression in vivo; and 2) the development of an in vitro transcription assay system, which currently is not available in the field.